Automatic sonar-beam-pattern plot

ABSTRACT

Means for making a polar plot of the beam pattern of a sonar transducer array. A sonar transmitting transducer is suspended from a long boom aboard a ship. A synchro transmitter is attached to the swivel point of the boom and electrically connected to a synchro receiver which rotates the polar-plot paper of a pen recorder. The input to the pen of the recorder is the output signal of the receiving sonar equipment on the ship, the beam pattern of the sonar equipment&#39;&#39;s receiving-transducer array being automatically recorded as the boom (and therefore the transmitting transducer) is rotated from port to starboard.

United States Patent [1.8. CI 340/5 C, polar-plot paper of a penrecorder. The input to the pen of the 340/6 R recorder is the outputsignal of the receiving sonar equipment Int. Cl .e. G015 3/00 on theship, the beam pattern of the sonar equipment's receivheld of Search340/3 R, 5, ing-transducer array being automatically recorded as the 5 Q43/l00 AP boom (and therefore the transmitting transducer) is rotated ft t b References Cited mm per 0 star oard UNITED STATES PATENTS3,292,139 12/1966 Einstein et al. 340/5 C swa -Mo rem/$44075? l 5 0054/1I su F/us lil z fl //4 5mm? TAHN5MI77'I/VG a Dre/(900.45 81; .0

50M? 5 mar/4o 4 i I I 22 24 I i 5mm? )lCE/l/l/VG ff fflj 27. 5 figiifi00/PMEN7 represented by the Secretary of the Navy AUTOMATICSONAR-BEAM-PATTERN PLOT 1 Claim, 1 Drawing Fig.

Primary Examiner-Richard A. Farley Attorneys-Richard S. Sciascia, LouisB. Applebaum and Philip Schneider Gregg, Jr. et al ABSTRACT: Means formaking a polar plot of the beam pattern of a sonar transducer array. Asonar transmitting transducer is suspended from a long boom aboard aship. A synchro transmitter is attached to the swivel point of the boomand electrically connected to a synchro receiver which rotates theAUTOMATIC SONAR-BEAM-PA'ITERN PLOT STATEMENT OF GOVERNMENT INTEREST Theinvention described herein may be manufactured and used by or for theGovernment of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention relates to sonar beam patternmeasurements and especially to an improved means for automaticallyobtaining a polar pattern for a sonar transducer array.

The present method for obtaining beam amplitude versus azimuth angle forsonar receiving transducer arrays is a long,

. tediousjob. A sound source is suspended from a long boom on the shipand sound level meter readings from the test set are recorded for eachof the preformed beams (e.g., the SQR-l3 sonar set has 18 preformedbeams) at one degree increments. The boom is moved manually and anchoredto the lifeline stanchion by means of two 95-inch lines attached to theboom. The azimuth of the boom is measured visually with a transit.

The lines used to anchor the boom stretch while positioning the boom;jockeying the boom and retying the lines consumes an inordinate amountof time. An average of only four boom positions per hour is possiblewhen using this method. Complete beam-pattern measurements of theforward dome over approximately 300) take about 75 hours.

The mid-dome measurements are further complicated by the fact that theswivel point of the boom does not coincide with the center of the domebecause of the superstructure of the ship. The swivel points for themid-dome are located on the port and starboard sides of the bridgesuperstructure and in each position, the swing of the boom is 180.Assuming that an hour is spent to measure 4, 45 hours will be requiredfor each side, thereby requiring a total of about 165 hours to obtainall data for beam-pattem measurement,

STATEMENT OF THE OBJECTS OF THE INVENTION An object of this invention isto increase the speed and ease with which polar beam patterns of sonartransducer arrays can be made.

This and other objects and advantages are accomplished by suspending asonar transmitting transducer from a boom aboard a ship and attaching asynchro transmitter to the boom so that both rotate together. Thesynchro receiver rotates the polar-plot paper of a pen recorder whoseinput is the output of the sonar receiving equipment aboard the ship.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a block diagram ofthe invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT single beam is selected by meansof its beam selector SWItCh."'

A long boom 12 is mounted to swivel about a king post aboard a shipcarrying a sonar set having a receiving transducer array with a numberof preformed beams, e.g., l8 preformed beams. A sonar transmittingtransducer 14 is hung from the end of the boom 12 so that the transducer14 lies under the ocean surface. The transmitting transducer 14 may befed from sonar transmitting equipment 26 aboard the ship.

A syncrho transmitter 16 is mounted on the swivel point of the boom 12and is electrically connected to a synchro receiver 18 which is, inturn, mechanically connected to a polar plotter 20. The latter is a penrecorder using polar plotting paper which is rotated by the synchroreceiver 18. (The polar plotter may, for example, be the Bruel and KjaerModel 2305, Graphic Level Recorder.")

In operation, the sonar receiving set is switched on and a The boom 12is swung to port and signals are emitted by the sonar transmittingtransducer 14. These signals are received by the receiving transducerarray 22 and processed by the sonar receiving equipment 24. The outputof the latter is a signal level which is fed to the pen of the polarplotter 20 which records it on the polar paper at the correct angle.Other signal levels are recorded on the paper at the proper angle as theboom 12 rotates from port to starboard. A polar plot of signal levelversus azimuth angle is thus automatically produced by the equipment.

Alignment of the equipment is very simple. A protractor is mounted onthe king post and is oriented for 0 on the ship's fore-and-aft centerline. With the axis of the boom along this line, the polar paper's 0line is placed directly under the pen point. This completes thealignment procedure.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

I claim: 1. In combination with sonar transmitting equipment, sonarreceiving equipment having a receiving transducer array which forms atleast one beam, said equipment being located nonrotatably aboard a ship,and automatic beam pattern measurement apparatus comprising:

swiveling boom means one end of which extends beyond the sides and bowof said ship;

sonar transmitting transducer means attached to said one end of saidboom so that the transducer means lies in the water;

synchro transmitter means coupled for rotation with said swiveling boommeans so that there is a one-to-one correspondence between the angularpositions of said boom means and said synchro transmitter means;

polar plotter means connected to receive and record the output signal ofsaid sonar receiving equipment on polarplot paper; and

synchro receiver means connected to said synchro transmitter means forrotation in synchronism therewith and mechanically coupled to said polarplotter to rotate said polar-plot paper.

1. In combination with sonar transmitting equipment, sonar receivingequipment having a receiving transducer array which forms at least onebeam, said equipment being located nonrotatably aboard a ship, andautomatic beam pattern measurement apparatus comprising: swiveling boommeans one end of which extends beyond the sides and bow of said ship;sonar transmitting transducer means attached to said one end of saidboom so that the transducer means lies in the water; synchro transmittermeans coupled for rotation with said swiveling boom means so that thereis a one-to-one correspondence between the angular positions of saidboom means and said synchro transmitter means; polar plotter meansconnected to receive and record the output signal of said sonarreceiving equipment on polar-plot paper; and synchro receiver meansconnected to said synchro transmitter means for rotation in synchronismtherewith and mechanically coupled to said polar plotter to rotate saidpolar-plot paper.